Terraform两难困境：未定义默认AWS Provider报错，定义后破坏区域Provider

• 未定义实际不需要的默认AWS Provider时，会收到默认Provider未配置的错误
• 定义默认AWS Provider后，模块中通过别名区域Provider覆盖的默认Provider逻辑被破坏

版本信息 #

以下两个Terraform版本均出现该问题：

Terraform v1.7.1
on darwin_arm64
+ provider registry.terraform.io/hashicorp/aws v5.31.0

Terraform v1.6.0
on darwin_arm64
+ provider registry.terraform.io/hashicorp/aws v5.31.0

测试场景 #

（所有<AWS_REGION>已替换为真实AWS区域标识，如us-east-1）

场景1：未指定默认AWS Provider #

Terraform配置：

# ./terraform.tf
terraform {
  required_providers {
    aws = {
      source = "hashicorp/aws"
      version = "~> 5.31.0"
    }
  }
  required_version = ">= 1.6.0"
}

根模块仅定义多区域别名Provider：

provider "aws" {
  alias = "<AWS_REGION>"
  region = "<AWS_REGION>"
}

# 注意：仅存在别名Provider，无默认AWS Provider

多区域模块传入对应别名Provider：

# ./modules.tf
module "provider_<AWS_REGION>" {
  source    = "./<AWS_REGION>"

  # 传入区域Provider，覆盖模块默认Provider
  providers = {
    aws = aws.<AWS_REGION>
  }
}

区域模块资源配置示例：

# 预期使用传入的默认Provider `aws`

# ./<AWS_REGION>/vpc.tf
resource "aws_vpc" "name_of_vpc" {
  # (配置内容)
}

本地状态文件片段：

# ./terraform.tfstate
{
  "version": 4,
  "terraform_version": "1.7.0",
  "serial": 1459,
  "lineage": "<SOME_GUID>",
  "outputs": {},
  "resources": [
    {
      "module": "module.provider_<AWS_REGION>",
      "mode": "managed",
      "type": "<TERRAFORM_RESOURCE_TYPE>",
      "name": "<TERRAFORM_RESOURCE_NAME>",
      "provider": "provider[\"registry.terraform.io/hashicorp/aws\"]",
      # ...
}

执行terraform plan（init后）抛出错误：

错误信息（未指定默认Provider时）

│ Error: Invalid provider configuration
│
│ Provider "registry.terraform.io/hashicorp/aws" requires explicit configuration. Add a provider block to the root module and
│ configure the provider's required arguments as described in the provider documentation.

╷
│ Error: Invalid AWS Region:
│
│   with provider["registry.terraform.io/hashicorp/aws"],
│   on <empty> line 0:
│   (source code not available)

场景2：添加默认Provider #

添加默认Provider配置：

# ./provider.tf
provider "aws" {
  region = "<ARBITRARY_AWS_REGION>"
}

结果：
无报错，但所有区域模块都使用默认Provider的区域，而非传入的指定区域Provider。

场景3：手动修改状态文件的provider字段 #

在terraform.tfstate的provider值末尾添加. <AWS_REGION>后，执行命令抛出错误：

│ To work with
│ module.provider_<AWS_REGION>.<TERRAFORM_RESOURCE_TYPE>.<TERRAFORM_RESOURCE_NAME>                                                                                                               
│ its original provider configuration at module.provider_us-east-1.provider["registry.terraform.io/hashicorp/aws"].<AWS_REGION>
│ is required, but it has been removed. This occurs when a provider configuration is removed while objects created by that     
│ provider still exist in the state. Re-add the provider configuration to destroy                                              
│ module.provider_us-east-1.<AWS_REGION>.<TERRAFORM_RESOURCE_TYPE>.<TERRAFORM_RESOURCE_NAME>,                                                                                                    
│ after which you can remove the provider configuration again.

场景4：模块资源手动指定provider #

在每个区域模块的所有资源中添加provider = aws.<AWS_REGION>，抛出错误：

Error: Provider configuration not present

场景5：结合场景3和场景4 #

仍抛出相同错误：

Error: Provider configuration not present

内容的提问来源于stack exchange，提问作者Neil